Configuration

The configuration file can be one of these files

• jampack.config.js (in ESM or CJS format)
• jampack.config.mjs
• jampack.config.cjs
• config/jampack.config.js (in ESM or CJS format)
• config/jampack.config.mjs
• config/jampack.config.cjs

Or in a top-level jampack property in your package.json.

Example

// jampack.config.js

export default {
  image: {
    compress: false,
  },
};

Options

Available in config-types.js.

export type WebpOptions = {
  effort: number;
  mode: 'lossless' | 'lossly';
  quality: number;
};

export type Options = {
  html: {
    /*
      jampack adds a little bit of css to make
      image keep correct aspect ratio after adding
      image dimensions.
      ":where(img){height:auto}"
    */
    add_css_reset_as: 'inline' | 'off';
  };
  image: {
    embed_size: number;
    srcset_min_width: number;
    external: {
      process:
        | 'off' // Default
        | 'download' // Experimental
        | 'cdn-srcset-when-possible' // Not implemented
        | 'add-dimensions-only'; // Not implemented
      src_include: RegExp;
      src_exclude: RegExp | null;
    };
    compress: boolean;
    jpeg: {
      options: {
        quality: number;
        mozjpeg: boolean;
      };
    };
    png: {
      options: {
        compressionLevel: number;
      };
    };
    webp: {
      options_lossless: WebpOptions;
      options_lossly: WebpOptions;
    };
  };
};

Default values

Available in config-default.js.

import { Options } from './config-types.js';

const default_options: Options = {
  html: {
    add_css_reset_as: 'inline',
  },
  image: {
    embed_size: 1500,
    srcset_min_width: 640,
    external: {
      process: 'off',
      src_include: /^.*$/,
      src_exclude: null,
    },
    compress: true,
    jpeg: {
      options: {
        quality: 75,
        mozjpeg: true,
      },
    },
    png: {
      options: {
        compressionLevel: 9,
      },
    },
    webp: {
      options_lossless: {
        effort: 4,
        quality: 77,
        mode: 'lossless',
      },
      options_lossly: {
        effort: 4,
        quality: 77,
        mode: 'lossly',
      },
    },
  },
};

export default default_options;

Technical notes

Jampack is using Nate Moore’s proload package to load configuration.